sciencehabit writes: Researchers have identified three genetic mutations that appear to have helped humans surive in the frigid climate of Siberia over the last 25,000 years. One helps the body's fat stores directly produce heat rather than producing chemical energy for muscle movements or brain functions, a process called "nonshivering thermogenesis." Another is involved in the contraction of smooth muscle, key to shivering and the constriction of blood vessels to avoid heat loss. And the third is implicated in the metabolism of fats, especially those in meat and dairy products—a staple of the fat-laden diets of Arctic peoples.